This SBIR Phase I project is designed to adapt a Giant Magneto-Resistive (GMR) sensor device into a "spintronic" multianalyte biosensor for pathogen detection. The potential value of biosensor technology is being recognized for a wide variety of applications, from medical diagnostics to countering bioterrorism. This project will focus on developing GMR immunoassays to detect common bacteria and protozoa in water supplies. Magnetic nano/microparticles present advantages as labels for biomolecule binding, including stability and low background signal. This project will provide improved biomolecule coupling technology for biosensor applications of the GMR microelectrode array under development by NVE Corp. and the paramagnetic microbeads under development as labels by the Naval Research Laboratories for the Bead Array Counter (BARC) biosensor system. The Phase I effort will include the synthesis and use testing of photochemical and electrochemical polymer derivatives for binding monoclonal and polyclonal antibodies to the silicon nitride surface and magnetic particles respectively. Signal/noise properties will be measured by fluorescent and magnetic assay methods and shown to be equal or superior to currently used assays. These Phase I results are expected to provide a solid technical background for optimizing the biomolecule immobilization chemistry in Phase II, as well as new, but related latent-reactive polymers for enhanced microfluidic channel coating and lid adhesion for the GMR biosensor flow cell. Development of a functional low cost, portable GMR biosensor for pathogens will aid human health by allowing quick analysis of local water supplies in the field, thereby minimizing diarrheal infections. [unreadable] [unreadable]